Electrically-operated toothbrush



Dec. 8, 1959 J. P. HussAR ELECTRICALLY-OPERATED TOOTHBRUSH Filed May 8, 1956 w A H w is fiINVENTOR.

United States Patent 2,915,912 ELECTRICALLY-OPERATED TOOTHBRUSH Joseph P. Hussar, Weymouth, Mass., assignor to Leslie N. Baker, Scituate, Mass.

Application May 8, 1956, Serial No. 583,454 6 Claims. (Cl. 74--423) The present invention relates to an improved structure in an electrical toothbrush.

The present invention specifically relates to an electrically-operated toothbrush in which a rotatable brush is operated from a motor source through a series of gears and other elements which provide a suitable operating control over the rotating brush.

There has been a continuous development of electrically-operated toothbrushes. To date, however, structures devised have not been entirely satisfactory for operation intermittently over long periods of time. The difficulties encountered in constructing a satisfactory electrically-operated toothbrush include the fact that the brush itself must, of course, be of a very small size and must further be shaped to conform with suitable operating requirements. Among these requirements is the necessity of providing the brush which rotates with suflicient shielding so as to prevent its engagement with or rubbing of the inside wall of the users mouth.

Further, the structure must be sufficiently rugged, although small, to withstand substantial stresses on the driven shaft which rotates the rotating brush. These stresses may be applied to the driven shaft from almost any angle. Moreover, the bearing means which support this shaft must -be quite strong in nature; for in view of the very small size of the unit, the leverage action on the driven'shaft, causedby sideways motion of the brush, can bequite substantial.

Additionally, the structure must include provisions for slowing or stopping the rotation of the brush when an ex- -ce ss of pressure is applied to it. This is required in order to protect the user from gum injuries due to excessive speeds and pressures of the brush against the gums.

The present invention satisfactorily attains the objects enumerated above as well as other objects and further provides advantages not heretofore known. In the present invention there is provided a driving shaft which engages, through a set of bevel gears and a coaxiallymounted bushing on one of the bevel gears, a driven shaft. This driven shaft is securely mounted for free rotation and longitudinal movement on a pin with additional support being provided to the shaft by a bearing member. Compact means are provided between the bushing and the driven shaft for frictional engagement of the shaft with the bushing. This particular arrangement enables the driving shaft and gears associated therewith to continue at normal operating speed, although the driven shaft is disengaged from the driving shaft on the application of excessive pressure onto the brush. The present invention also provides by this structure the unit which is compact in nature and which may readily be assembled with a minimum of expense.

There is also provided in the present invention a novel means of securing the rotating brush to the driven shaft with this engagement being of such a nature as to permit a ready removal of the brush and its replacement by a new one. These and other features of the present invention will be more clearly understood when considered "ice in connection with the accompanying drawings in which:

Figure 1 is a partially cross-sectional side view of the invention,

Figure 2 is a cross-sectional elevation of the brush attached to the driving shaft,

Figure 3 is a modification of the brush and drive shaft, and

Figure 4 is a further modification of the brush and drive shaft.

Referring first to Figure 1, there is illustrated an electrically-operated brush having a casing generally indicated at 1. This casing may be made of any suitable material, but preferably is made of a plastic, such as polystyrene or acetate. Within this casing 1 there is provided a motor section 2 and a shaft section 3, which interconnects the motor section 2 with the head 4. A driving shaft 5 extends longitudinally through the shaft section 3 and is suitably mounted in it for rotation by one or more bearings 6. The shaft engages and is operated by a motor contained within the motor section 2. This motor is not shown, but it may be of conventional design and may receive a power supply through the cord 7.

The other end of this driving shaft 5 projects into a hollow opening 8 formed in the head 4. The end of this driving shaft 5 is formed into a beveled gear 9. A second bevel gear 10 operatively engages the first bevel gear 9. This second bevel gear 10 is secured in fixed relationby suitable means to the bushing 11. The bushing 11, which is coaxial with the gear 10, is provided with a central opening having a beveled end 12. This opening in the bushing 11 is coaxially aligned with the pin 13. This pin 13 is fixed in the wall of the head 4 and projects into the opening of the bushing 11. Coaxially mounted on the pin 13 and also coaxially positioned within the opening in the bushing 11, is the driven shaft 14. This driven shaft 14 is preferably hollow along its entire length, although it need actually be hollow only along a limited portion of its length. The driven shaft 14 is freely rotatable upon the pin 13 and is further movable longitudinally with respect to it. The driven shaft 14 is provided with a flared end 15 within the opening 8. This flared end 15 has a contour shaped to conform with the flared end of the opening within the bushing 11. These two flared surfaces, one on the driven shaft14 and one at the end of the opening in the bushing 11, are adapted to frictionally engage with one another when the driven shaft 14 is moved outwardly of the casing. If necessary, the surfaces of the driven shaft 14 and the flared or beveled portion of the bushing 11 may be roughened to facilitate the frictional engagement. A frictional engagement is normally maintained, unless other stresses are applied through the driven shaft 14, by means of the spring 16. This spring is preferably dome-shaped with a central opening symmetrical with the spring 16. The spring 16 is coaxially mounted on the pin 13 with its peripheral edges engaging the inner surface of the head section 4 at 17.

The bushing 11 and bevel gear 10 are secured in a fixed longitudinal position in one direction by the engagement of-the gear 9 with the gear 10 and in the other direction by the washer 19, preferably formed of steel, the ball bearing race 20 and the cap 21. The washer 19, ball bearing race 20 and cap 21 are all coaxially mounted on the driven shaft 14. The cap 21 is fixed by suitable means within an opening in the head 4. The ball bearing race 20 is positioned within this cap and is covered with the washer 19 interposed between the cap 21 and the bottom of the bushing 11. To prevent accidental dislodging of the cap 21, a shoulder 22 may be provided, which shoulder engages the cap with the wall of the head 4.

The bevel gears 9 and 10 may, if desired, be formed of 1. Q f 3 i frictional engaging surfaces. However, for a more positive drive, the bevel gear arrangement is preferred.

At the end of the driven'ishaft 14, there is secured a rotatable brush 2 4; as-illustratedin Figure 2. This brush,

is securedrto the driven shaft through a plate member 25. This plate member is secured to the end of the shaft '14, preferably by a: threaded stud 26 which threads into' the end of the driven shaft 14 and which is alsosecured to the plate 25 The plate 25 is preferably circular in plan view with a two level thickness as illustrated at 27 and 28 The brush 24 isprovided with a cap 29 having a recess which conforms to the stepped configuration of the-plate 25. This FGCfiSSflS positioned under a lip 30 so lar in plan View has aprojecting section shaped similar to a Philips head screw driver as illustrated at 42. This engaging; member 42 projects into a complementary recess within the cap. 43.- of the brush 44; r

, The cap'of the brush 44 is; secured to the plate 40 with the element. 42 in its engaging position by the lips 45' which overlap the plate 40- A; further modification ofthis structure is illustrated at Figure. 4 in. which the plate 5.0 is secured. to. the driven shaft. 14 by a threaded stud 51 projecting from the upper 2. A structure as setforth in claim l wherein said pin is mounted on a casing and projects into a coaxial opening in said driven shaft and said driven shaft has a limited longitudinal movement.

3. A structure as set forth in claim 1 wherein said tensioning means comprises a dome-shaped spring coaxial with said pin and having one surface engaging the end of said driven shaft.

4. 'A structure as set forth in claim 1' wherein said toothbrush is provided with a casing having'anenclosed head, said pin mounted: within said head and said driven' shaft projecting from said casing.

5. Arr electrically-operated toothbrush having a casing with walls forming. an enclosed chamber, a driving shaft with a first bevel gear at the end thereof mounted for rotation Within said casing, a second bevel gear interengaging the first bevel gear and having a bushing coaxially secured thereto with said bushinghaving anopening with the driven shaft 14. Theplate 40, which may be circu a flared friction engaging surface,.alhollow driven shaft coaxially positioned within said bushing, a fixed. pin projecting into said' hollow driven shaft and supporting itfor free rotation and limited longitudinal movement, said driven shaft having, a friction engaging surface: adapted on longitudinal movement outwardly of. said casing to engage said surface of said bushing, anditensioning means normally tensioning said surfaces intoengagement;

6. Anelectrically operated toothbrush. having a drive shaft with a first bevel gear at the end thereof, a pin surface of the. plate. into the'threadedrecess of the driven 1 shaftv 1 4. The plate 50,, unlike those previously mentioned, is. rectangular in shape and is positioned within ajrecess in the cap-52 whichrecess has a corresponding rectangular shape A lip: 53, about the periphery of the recess, secures the plate Sil to the brush 52.

Having now described my invention, I claim:

1. An electrically-operated toothbrush having a drive shaft with a first bevel gear at the end thereof, a second mounted normal to and in the same. plane as the axis of'said' shaft, a driven shaft,,a bushing and a second bevel gear each coaxial with said pin, said driven. shaft freely rotatabieon said pin, said bushing, and second' bevel gear interengage'd, 's-ai'd' first and second bevel gears interenbevel gear interengaging, the first and having a bushing secured thereto, said bushing; having a beveled opening with a frictionally-engaging surface, a pin coaxially aligned witlr said opening, adriven shaft. freely rotatable on and longitudinally movable with respect to said pin,

said: driven shaftprojecting through said opening with a flared frictional engaging surface, and tensioning means normally tensioning; said surfaces into engagement.

gagd} frictional engaging means provided in part on said driven shaft and in part on said. bushing, and tensioning means normally maintaining said-bushing and driven shaftin frictional engagement.

References Cited in the file of this patent UNITED STATES PATENTS 1,397,365 Due ,Mflflh hi-.. Feb. 14, 1933 ,005,3 7 Doll s June 18,1935 2,401,992 Waller t June 11, 1946 2,723,014 Locke Nov. 8,. 1955 FOREIGN PATENTS 919,905

Germany Nov. 8;, 1954 

